This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-326876, filed Oct. 26, 2000, the entire contents of which are incorporated herein by reference.
This invention relates to a solvent distillation apparatus, and more particularly to the structure of a distillation apparatus for preparing an anoxic, dehydrated solvent that is used when synthesizing molecular asymmetric catalysts.
The creation of an organic substance having a new function bears an important part in maintaining and developing an advanced civilized society. Accordingly, techniques for synthesizing organic substances are becoming more and more important. In particular, the establishment of an organic synthesizing process is desired, which is of a resource/energy-saving and environmentally conscious type, and thus kinder to the world""s future generations.
Throughout the world, attention is now being paid to molecular asymmetric catalysts as one of the core techniques for substance conversion, since they are highly active. Molecular asymmetric catalysts are crucial substances for the creation of functional organic substances having new qualities. In recent years, high quality molecular asymmetric catalysts are being developed one after another. Although the number of industrialized reactions using molecular asymmetric catalysts is not so large at the present stage, as compared to the number of fermentation processes using microbes and employed in the Japanese traditional industries, it is expected to increase hereafter at an accelerating speed. It is very possible that molecular asymmetric catalysts will be widely used in the material science industry, as well as in the medical/agrichemical industries.
When synthesizing a molecular asymmetric catalyst, extremely strict management of the conditions is required. To prepare a highly active molecular asymmetric catalyst, an anoxic, dehydrated solvent, for example, is indispensable. In the prior art, the following process is employed to prepare an anoxic, dehydrated solvent. A solvent as a raw material is refluxed for several hours in the atmosphere of an inactive gas in the presence of an appropriate drying agent, thereby removing the low-boiling-point component from it. After that, the thus-obtained solvent is distilled, and an anoxic, dehydrated solvent is collected as a condensate.
However, the above-described conventional refining process has these problems: (a) it is not highly productive; (b) the refining equipment requires a large installation area; (c) it has a small product yield; (d) the degree of sealing of the refining equipment is not so high, and hence the residual amounts of oxygen and water are high; (e) since a tapered joint is used at each connection of component parts of the equipment, and grease is used to seal the joint, contamination due to the grease is inevitable; and (f) it is not easy to attach each component part to the equipment or detach it therefrom.
The present invention has been developed in light of the above-described problems in the conventional process for refining an anoxic, dehydrated solvent. It aims to provide a solvent distillation apparatus capable of preparing an anoxic, dehydrated solvent of high purity with high yield, and with high productivity.
To attain the object, there is provided a solvent distillation apparatus comprising:
a distilling flask to be supplied with a solvent before it is refined;
a collecting flask for collecting the solvent after it is refined;
a fractionating column connected to a mouth of the distilling flask;
a reflux condenser having a middle portion thereof connected to an upper end of the fractionating column, and an upper end thereof provided with an outlet for a non-condensable gas; and
a condensate reservoir connected to a lower end of the reflux condenser,
wherein:
the condensate reservoir has a base thereof connected, via a first flow adjusting valve, to a portion of the fractionating column near a lower end thereof, and also connected to the mouth of the collecting flask via a second flow adjusting valve; and
the condensate reservoir has an inlet provided near a base thereof for blowing therethrough an inactive gas.
Using the above apparatus, a solvent is refined in the following manner. First, a to-be-refined solvent is introduced into the distilling flask. Further, a drying agent is introduced into the distilling flask. After the distilling flask and the collecting flask are connected to the main body (which consists of the fractionating column, the reflux condenser and the condensate reservoir), an inactive gas is used to purge the interior of the apparatus.
After that, the distilling flask is heated while introducing cooling water into the reflux condenser, with the first and second flow adjusting valves is opened and closed, respectively. Vapor of the solvent is mainly condensed in the reflux condenser. The resultant condensate is returned from the condensate reservoir to the distilling flask through the first flow adjusting valve. At the same time, an inactive gas is blown into the condensate collected in a base portion of the condensate reservoir, thereby executing gas bubbling to purge any non-condensable gas contained in the solvent. The reflux process of the solvent eliminates any non-condensable gas therefrom. During this process, moisture contained in the solvent is also eliminated as a result of reaction between the drying agent and the solvent.
After finishing the reflux process, the first and second flow adjusting valves are closed and opened, respectively. As a result, a highly purified condensate is collected in the collecting flask.
In the solvent distillation apparatus of the invention, any non-condensable gas is purged from a condensate collected in a base portion of the condensate reservoir, by blowing an inactive gas into the condensate to bubble it while the solvent is refluxed. As a result, the purity of the condensate can be enhanced efficiently.
Preferably, the distilling flask is connected to a lower end of the fractionating column by a first glass flange with a groove for an O-ring, and the collecting flask is connected to the base of the condensate reservoir, via a second glass flange with a groove for an O-ring and the second flow adjusting valve in this order.
In the solvent distillation apparatus constructed as above, the distilling flask and the collecting flask can be easily attached to and detached from the main body. In addition, any grease for sealing connections is not required, and hence the refined product is free from contamination by-the grease.
More preferably, O-rings made of polytetrafluoroethylene are fitted in the respective grooves.
Further preferably, the fractionating column, the reflux condenser and the condensate reservoir are formed integral as one body without any couplers.
In the solvent distillation apparatus constructed as above, the gas-tightness of the apparatus is improved, and the purity of the condensate can be enhanced.
Yet preferably, the fractionating column has a double barrel structure including inner and outer tubes, an annular space defined between the inner and outer tubes being set at a vacuum pressure. The inner surfaces of the annular space are plated with silver. A number of wiggles are attached to an inner peripheral surface of the inner tube.
The fractionating column constructed as above has a high heat insulating property and hence enhances the efficiency of fraction.
In the fractionating column constructed as above, the glass bellows absorbs the difference in thermal expansion between the inner and outer tubes, thereby increasing the durability of the apparatus.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.